SQLITE: Get Current time in millis and fit into 32 bit int.

I need a 32 bit time identifier. At the moment in sqlite strftime('%s','now') is being used in a trigger to set a 32 bit time identifier. Turns out a resolution of one a second doesn't cut it for our application so I want to move to milliseconds and cut off the left side bits to retain 32 bits in total. I don't need to be able to use the result as a datetime any more as it will be concatenated into an identifier. The string doesn't need to be 32 bit, the number it represents however must be.